As the geometry of semiconductor devices shrinks, accuracy of pattern definition for critical dimensions, such as gate line width, trench depth or contact diameter become a challenging topic. For pattern definition, in addition to photolithography, etch is one of the important operations needs to be addressed.
Etch is used to sculpture a film to form a desired pattern and various types of etch processes are adopted accordingly. A reactive ion etch (RIE) is a type widely introduced in the field, especially in a directional patterning process. However, draw backs such as loading effect and selectivity cause undesired deviation and poor uniformity. Defects like film residues or corner rounding formed after the etch process impact the performance of a product yield or even the reliability. Thus, a high selectivity and pattern insensitive etch is required in order to manufacture an integrated circuit.